Snap25b(I67T)错义突变通过抑制下丘脑炎症改善肥胖的机制研究

肥胖严重危害人类健康。下丘脑炎症被认为是导致肥胖的源头，但机制未明。突触相关蛋白25kDa(SNAP25)是介导细胞外分泌的关键蛋白。申请人前期发现Snap25b(I67T)错义突变(Snap25be(I67T)1)小鼠正常饮食时呈体重和体脂含量降低、能量消耗增加、胰岛素敏感性增强及循环和下丘脑炎症水平下降表型。为进一步探索，本项目拟(1)高脂喂养Snap25be(I67T)1小鼠鉴定肥胖抵抗表型；采用CRISPR-Cas9基因编辑和下丘脑定位注射构建下丘脑选择性Snap25be(I67T)1小鼠，验证中枢的关键影响。(2)用原代小胶质细胞，利用信号通路磷酸化抗体芯片、GST Pull-down等方法探索SNAP25b介导下丘脑炎症反应的分子机制。本项目欲阐明Snap25b(I67T)错义突变通过抑制中枢炎症改善体重和代谢的机制，为明确SNAP25b作为肥胖检测和干预的新靶点提供实验依据。

The prevalence of obesity is increasing worldwide, which is threating human’s health. Hypothalamic inflammation has been considered as one of the most important causes of obesity. However, the underlying mechanism has not been well clarified. Synaptosomal-associated protein 25 kDa (SNAP25) is a key protein that mediates extracellular secretion. We previously found that Snap25b (I67T) missense mutant (Snap25be(I67T)1) mice showed a phenotype of decreased body weight and body fat percentage, increased energy expenditure, increased insulin sensitivity, and decreased levels of inflammatory cytokines in both blood and hypothalamus on the premise of unchanged food intake and activity. To further explore the mechanism of SNAP25b in regulating weight and metabolism by inhibiting hypothalamic inflammation, we will firstly verify the obesity resistance phenotype of Snap25be(I67T)1 mice by high fat diets. Furthermore, we will establish selective hypothalamic Snap25be(I67T)1 mice by CRISPR-Cas9 gene editing and hypothalamic localization injection technology to explore the leading effect of central SNAP25b on obesity and metabolism. In addition, primary microglial cells will be used and we will apply GST Pull-down technology to explore the molecular mechanism .of SNAP25b mediates hypothalamic inflammation. The purpose of the current project is to clarify the effect of Snap25b (I67T) missense mutation on obesity and metabolism, thus providing experimental evidence for SNAP25b as a new laboratory indicator and therapeutic target for obesity.